Apparatus for maintaining the



M. H. oLs'rAD ETAL Re. 22,553

Oct. 3, 1944.

APPARATUS FOR MAINTAINING THE DESIRED TEMPERATURE OF LIQUIDS Original Filed Aug. 19. 1942 INVENTOR Reissued Oct. 3, 1944 APPARATUS FOR MAINTAINING THE DESIRED TEDIPERATURE OF LIQUIDS.

Martin H. Olstad. Bayside, and Allan E. Williams,

White Plains, N. Y assig'nor! to Niagara Blower Company, New York, N. Y.. a corporation of New York Original No. 2,321,933, dated June 15,1943, Serial- No. 455,394, August 19, 1942. Application for reissue October 11, 1943, Serial No. 505,866

8 Claims.

This invention relates to apparatus for maintaining the desired temperature of a fluid and more particularly is shown, as an example of its use, as embodied and carried out in a heat exchanger for maintaining the desired temperature of quenching oil used in tempering steel. However, the invention can be used in conjunction with fluids other than quenching oils and the invention is therefore not to be construed as limited to any particular fluid to be treated.

The original application was a continuation in part of our copending application Serial No. 419,412, flied November 1'7, 1941, for Apparatus for maintaining the desired temperature of a. liquid, now Patent No. 2,296,946, dated September 29, 1942.

-In the tempering .of steel, the steel at temsteel. The quenching oil may include a large percentage of lard oil which may deposit on the heat transfer surface of the cooler in the form' of a wax.

This wax builds up until the heat transfer between the cooling surface and the quenching oil is greatly reduced and the capacity of the cooler greatly diminished.

With oil cooling systems now in use, no adequate provision is made'for dewaxing the cooling surface and also, with systems nowin use.

while it is possible to cool th quenching oil bath, no provision is made for heating the bath; Therefore, at the start of the operation of tempering steel, or in shifting to higher temperature quenching, it ha. been the practice for the operator to pass a few batches of hot steel through the bath merely to bring. the bath up to the desired quenching temperature. The passing of hot steel merely to bring up the temperature of the quenching bath to that desired in volves, of course, waste labor and also the possible loss of a large quantity of steel in the event that it cannot be retempered at the de-.

sired temperature.

It is one of the principal objects of the present invention to provide a simple and efflcient apparatus adapted to cool a fluid in which the cooling effect is obtained from the evaporation of water, thereby to sreatly reduce the amount of cooling water necessary for the operation of the apparatus.

Another object of the invention is to provide such apparatus in which the temperature of the liquid being treated is maintained within very close limits.

Another object of the invention is to provide such apparatus which is fully automatic in maintaining the desired temperature of the fluid being treated.

Another object of the invention is to provide a simple and effective control for the minimum temperature of the fluid being treated by the adjustment of the character of the air supplied to the apparatus. Another object of the invention is to provide such apparatus in which, where the cooling effect is obtained from the evaporation of water, such control can be eflected entirely automatically in response to the temperature of the spray water, being in turn responsive to the temperature of the liquid being treated.

Another object is to provide such apparatus in which, where the cooling effect is obtained from the evaporation of water, the amount of moisture evaporated to provide the cooling effect is reduced to a minimum.

Another object of the invention is to provide for dewaxing the cooling surface, when used for cooling quenching oil, so as to insure theproper heat transfer between the cooling surface and the quenching oil at all times.

Another object of the invention is to provide for heating the quenching oil, when desired, so as to bring it up to the proper temperature for use in tempering steel, and thereby avoid trol of the cooling eii'ect of the apparatus.

Another object is to maintain the apparatus under such conditions that no substantial amounts oflard oil are precipitated out on the cooling surface, when used for. cooling quenchin: oil.

Other objects are to provide such apparatus which is simple and in nsive in construction severe and constant use without .getting out oforder or requiring repairs.

In the accompanying. drawing: Fig.1 is a diagrammatic perspective view of a heat exchanger embodying and carrying out the invention. 1

Fig. 2 is a fragmentary, vertical, transverse section, taken on line 2-2, Fig. 1.

Fig. 3 is a fragmentary side elevation of a modified form of heat exchanger and showing a different way of supplying heat to paratus.

Fig. 4 is a fragmentary side elevation of a heat exchanger showing a further modified form of the invention.

Fig. 5 is a fragmentary view similar to Fig. 4 showing a still further modified form of the invention.

The heat exchanger shown. by way of example in the accompanying drawing, is particularly designed for maintaining the desired temperature of the quenching oil used in tempering steel, in which it operates at most times to cool the quenching oil, provision also being made, however, for heating the quenching oil and also to maintain the desired minimum temperature of the water used for cooling, through the heating means.

The apparatus shown is designed to eflect cool-' ing through the evaporation of water and includes a sheet metal casing] whichis mounted upon a tank I forming the base ofthe casing. this tank I containing a body of water I which is evapora to provide the. cooling eifect. The tank I is preferably extended. beyond one end of the casing 5, as indicated at I, and this extension isshownasprovided withatop 9.

A plurality of fan housings II are mounted in the upper part of the casing 8, the inlets of these fan housings being in communication with the interior of the casing Use as to exhaust air therefrom. A common shaft Ii extends through the several fan housings II and is shown as driven by a motor I2 mounted on a bracket II at one end of the casing I. Within each fan housing the shaft ll carries a fan ll of any suitable conthe apand which will stand upunder conditions of recirculation air duct, is also moved to restrict the air discharge duct thereby to reduce the amount of air exhausted to the atmosphere in relation to the amount of air recirculated through the recirculation duct 2|.

The fresh air damper 30 is provided with an operating lever 22 which projects downwardly and the recirculation damper Si is provided with a lever 33 which projects upwardly. The free ends of these levers 32 and 33 are connected by a bar N, the central part of which is connected 1 by a link with the arm 36 of a damper mothe body I of spray water in the tank 6, this.

tor II, this damper motor 31' being shown as being mounted on a bracket 38 secured to the exterior of the duct 22. The control line '40 to the damper motor 31 connects with a thermostat ll, the sensitive parts of which are immersed in.

spray water being heated, as hereinafter described, in response to the temperature-of the 1 quenching oil or other fluid being cooledand which quenching oil leaves the apparatus through a return line 42, this return line discharging the ing 5 by the fan wheels i4.

str'uction, these fans drawing the air from the- 2 interior of the casing I and discha ng it through the outlets ll of the several fan housings which project upwardly through the top of the eas- These outlets discharge theair into a vertical duct 2|,the upper end of which forms an air discharge duct for exhausting the air .to the outer atmosphere. A horizontal recirculation air duct 2| communicates with one side 01' the vertical duct 22, this recirculation air duct discharging into a vertical duct 22 arranged inrear of the casing I and this vertical duct 22 being provided with a lower horizontal leg 22 which is in communication with the lower part of the casing I immediately above the tank I. A cold air intake duct 26 also discharges into the vertical duct 22, this cold air intake duct being prefer ably in horizontal alinement with the recirculationairductfl. v I I Means are provided for delivering different proportions of cold outside air from the duct 28 and recirculated or return air from the duct 2! into the duct 22. For this P rp se a fresh air p r ll is arranged in the cold outside air position to close the opening into the recirculation air duct 2l. This recirculation damper Ii,

Immediately below the bank of coils N a second bankof 00115 45 isarranged, this second bank of coils 45 being supplied with steam from a steam line 46, the condensate being withdrawn from these .coils through a line 41. The steam or other heating medium supplied to the coils ll is under control of a valve 48 which is actuated in response to an immersion thermostat 49; the sensitive parts of which are immersed in the body of water 1 contained within the tank 6.

The steam valve 48 can also be placed under manual control and for this purpose the immersion thermostat I9. is shown as connected to the steam valve it by a wire 50, and the other wires ii and 52 connected, respectively, with the steam valve 48 and immersion thermostat 49 are shown as connected through a manual switch 53 with the main power lines 54 and 55. While the steam coil 45 is shown for supplying heat, it will be understood that heat could be supplied by other means, as by a steam ejector 15 in the recirculating water line 6|, as shown in Fig. 3, or by a heating coil a immersed in the water I in the tank 6, as shown in Fig. 4, or by a coil "b arranged abovethe cooling coil 44, as shown in Fig. 5. Further, the control of the steam or other heating medium could be made responsive to an immersion thermostat 16, the sensitive parts I of which are'immersed in the quenching oil or other liquid leaving the apparatus through the line42,asshown in Fig. 4.

The water I to the tank {can be supplied in any suitable manner and is shown as maintained at a constant level by an overflow connection 58 in the upper part of the tank 6, this overflow 56 leading to a drain line 51 connected with the bottom part of the tank I. A drain valve 58 is provided in the drain line 51 between the tank I and the connection of this drain line 51 with the overflow line 58.

The water I in thetank 8 is withdrawnby a when moved away from the opening into the centrifugal spray water pump 60 and is dis- The quenching oil or other fluid to be charged through a vertical pipe 8| into a horizontal pipe l2 extending lengthwise through the interior of the casing above the bank of coils 44.

Assuming that the quenching oil is being used for tempering steel and that the heat exchanger forming the subject of the invention is operating .under heavy cooling load conditions, this hot quenching oil enters the bank of cooling coils 44 from the supply line 43 and is returned to the tempering bath through the line 42. The quenching oil so passing through the bank of coils 44 is arranged in the stream of air which, under heavy cooling load conditions, is drawn by the fan wheels l4 from the cold air intake duct 26 through the vertical duct 22 and horizontal leg 23 into the bottom of thecasing 5, this cold outside air being drawn vertically upward through the casing I and discharged by the fan wheels l4 into the air discharge duct 20. At the same time the body of water I in the tank 6 is being pumped higher wet bulb temperature and hence the evaporative cooling effect of the water and air by the spray water pump 80, through the pipes ll, 02 and II and issprayed onto the bank of coils 44 by the nozzles 84, the excess spray water oil passing through the bank of coils 44 is thereby subjected to evaporative cooling and leaves through the return line 42 in a cooled condition.

With a decrease in the cooling load upon the apparatus, as occurs between withdrawing a tempered batch of steel and the introduction of a batch of hot steel into the bath of quenching oil to be tempered, the falling temperature of the quenchiifioil passing through the bank of coils 44 effects a corresponding drop in temperature of the water sprayed over this coil and hence actuates the thermostat 4| and the damper motor I! connected to this thermostat through the control line to move the fresh air damper 30 toward its closed position and the recirculation damper 3| toward its open position. It will be understood, of course, that the thermostat 4| could be directly responsive to the temperature of the quenching oil or other liquid being cooled, as by arranging the thermostat 4| with its sensitive parts immersed in this quenching oil as shown in our said copending application Serial No. 419,412 (Patent No. 2,296,946), of which this is a continuation in part. When this occurs recirculation air from the air discharge duct 20 is drawn, together with the fresh air from the cold air intake duct 28. through the vertical duct.

22 and its horizontal leg 23 into the bottom of passing over the bank of coils 44 is reduced. .It will therefore be seen that the immersion'thermostat 4! in the spray water maintains a constant minimum temperature of the quenching oil by the inverse operation of the recirculation damper 3| and fresh air damper 30, a falling temperature of the quenching oil or other liquid being treated, and hence a falling temperature of the spray water, opening the recirculation damper 3| and closing the cold fresh air damper 30. This modulating control of the dampers 30 and 3| allows the intermediate position of these dampers to hold a constant minimum temperature of the quenching oil by the use of recirculated air and tempered cold fresh air. Therecirculation of the necessary amount of air from the air discharge duct 20 to the bottom of the casing 5 in so maintaining a constant minimum temperature of the quenching oil or other liquid being treated also keeps the amount of evaporated moisture to a minimum. The arrangement of the recirculation damper 3| in the airdischarge duct 20 also serves to reduce the amount of air exhausted through the outlet of the discharge duct 20 with an increase in the amount of recirculated air returned to the bottom of the easing 6.

The primary purpose of the immersion thermostat 4-9 in the spray water tank 6 (or the thermostat 16, Fig. 4, in the quenching oil) is to keep the water temperature above a predetermined minimum. With quenching oils, this minimum is in the range of to F., and by keeping'the spray water at this minimum temperature, the minimum amount of lard oil will be deposited out in the cooling coils 44. By setting the thermostat 49, or the thermostat 16, Fig'. 4, to maintain, through the steam coils 45, this minimum temperature of the spray water, the deposit of wax in the coils 44 is reduced to a minimum since it has been ascertained that at temperatures above 55' F. practically no lard oil will deposit out of quenching oils.

In the event that the temperature of the quenching oil drops below that required for properly tempering the steel, as at'the start of operation or in an extended period between tem pering operations, the immersion thermostat 49 isactuated by the lowering temperatures of the water 'l' in the tank 6 to open the steam valve 48 and admit steam to the steam coils 45. This thermostat 49 serves to maintain a constant min-,

, discharge duct 20, recirculation duct 2|, vertical duct 22, and horizontal leg 23 to the bottom of the casing 5, this air moving upwardly through the bank of coils 44 carry ng the quenching'oil or other liquid being treated'so as to heat the same. Since this recirculating air iss'aturated with moistureQthere is no evaporative cooling effect and hence. the quenching oil passing through the bank of coils 44 is heated so as to keep the bath of quenchinguoil at the desired minimum temperature. under all conditions of operation. The same effect is obtained throug the thermostat I6, Fig. 4. v If the cooling coils 44 which carry the quenchaway with the quenching oil.

While the invention has been described particularly in conjunction with the cooling of quenching oils, it will be understood that it is not 1 limited to this particular use but may be.used

in conjunction with any fluid to be treated as in-,

dicated in the accompanying claims. While the invention has also been illustrated as embodied in an evaporative type of heat exchanger, the

use of the spray water for evaporative cooling is not an essential feature of the invention in its broader aspect. I

From the foregoing it will be seen that the present invention provides a simple and eflicient l paratus for maintaining the desired temperavery close limits: which, where the cooling eflect ls'obtained from the evaporation of water, has a high cooling capacity with a minimum consumption of cooling water: and which will prevent the fluid being treated from dropping below the desired minimum temperature. Further, when the cooling surfaces become waxed up due to the deposit of any material. such as lard ofl, on the cooling surface, this surface can quickly and easily be dewaxed. e We claim as our invention:

1. A heat exchange device for maintaining a fluid in a selected temperature range determined ,let. a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributinga stream of water over said cooling coil to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the s id stream of fluid to be cooled through said cooling coil. said streams of air and water being nor- I a ingoil become me up internally due to the ranged to forces stream of air from said inlet, through said chamber'and out through said outlet. a cooling coil arranged in the stream of air stream offluid to be cooled through said cooling coil, said streams of air and water being nor- I mally heated through heat derived from said mostat means responsive to the temperature of thereof from falling below said temperature ,ture of a fluid, such as quenching oil, within one of said streams to adjust said means for applying heat to prevent the temperature of said fluid in said cooling coil from falling below said range. comprising means forming a chamber hav-' ing an air inlet and an air outlet, a fan arranged to force a stream of air from said inlet; through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a stream of water over said cooling coil to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the said stream of fluid to be cooled through said cooling coiLrecirculation means for conducting a part of the stream of air leaving said-chamber back to said air'inlet, means for controlling the amount of air returning through said recirculation means, a heating coil arranged in the stream of air passing through said chamber. said streams of air and water being normally heated through heat derived from said stream of fluid pasdng mally heated through heat derived from said stream of fluid passing through said. cooling coil,

, recirculation means for conducting a partof the streamofairleavingsaidchamberbacktosaid air inlet, means for applying heat to said stream offluid, and thermostat means responsive to the temperatureofoneois'aidstreamstoadiustthe amoimtofairsoconductedbackbysaidrecireulation means and also said means for applying heattosaidstreamoffluidtopreventthetemperatureofsaidfluldinsaiiicoolingcoilfrom falling below said temperature range. tflheatexchangedeviceformaintaininga fluidinaselectedtemperaturerangedetermined r n e. comprising means achamber" ha'llll' ing below said temperature range.

' 4. a heat enchangedevice for,maintainlng a a fluid in a selected temperature range determined by the character of the fluid by cooling a stream of said fluid and preventing the temperature .thereof from falling below 'said temperature ran e-comprising means'forming achamber having an air inletand an air outlet, a fan arrangedtoforceastreamofairfromsaidinlet,-

through said chamber-and out through said outlet,acoolingcoilarrangedinthestre'amofair passing through said means for discharging .and distributing water over said coolingcoiltowetthee'xterior oi'saidcooiing'coil and to evaporate and absorb heat. therefrom,

means forcontinuously conducting the said streamoffliddtobecooled'throughsaidcoolingcoii,means forapplyingheattosaidstream flmandthermostatmeansdirectly responsivetotintemperatureof-saidwa-tertoadiust mean'sforapplyingheattopreventthetemperature thereoi from falling below said temperature range.

5. A heat exchange device for maintaining a fluid in a selected temperature range determined by the character the fluid by cooling a stream of said fluid and preventing thetemperature thereof from falling below said temperature range, comprising means forming a chamber having an air inlet and an air outlet. a tan arranged to force a stream of air from said inlet, through said chamber and'out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a stream of water over said cooling coil to wet the exterior of said cooling-coil and to evaporate and absorb heat therefrom, means for continuously conducting the said stream 0! fluid to be cooled through said cooling coil, said streams of air and water normally being heated through heat derived from said stream oi'fluid passing through said cooling coil, means ior applyi s heat directly to said water, and thermostat means responsive to the temperature of one of said streams to adjust said means for applying heat to said water to prevent the temby the character of the fluid bycooling a stream of said fluid and preventing the temperature perature of said fluid in said cooling coil from falling below said temperature range.

6. A heat exchange device for maintaining a fluid in a selected temperature range determined by the character of the fluid by cooling a stream or said fluid and preventing the temperature" thereoi from falling below said temperature range, comprising means forming a chamber having an air inlet and chair outlet, a fan I arranged to force a stream of air from said inlet, through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for continuously conducting the said stream of fluid to be cooled through said cooling coil, said stream thereof from falling below said temperature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream of air from. said inlet, through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for conldnuously conducting the said stream of fluid to be cooledthrough said cooling coil, said stream of air being normally heated through heat derived from said stream of fluid passing through said cooling coil, recirculation means for conducting a part of the stream of air leaving said chamber back to said air inlet, means for controlling the amount of air returning through said recirculation means, means for applying heat to said fluid, and thermostat means responsive to the temperature of one of said streams to adjust said means for applying heat to prevent the temperature of said fluid in said 0001- ing coll from falling below said temperature range. a

8. A heat exchange device for maintaining a fluid in a. selected temperature range determined bythe character of the. fluid by cooling a stream of said fluid and preventing the temperature thereof from falling below said temperature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream of airfrom said inlet, through said chamber and out through said outlet, a cooling coil arranged in tin streamof air passing through said chamber, meansrtor continuously conducting the said stream of fluid to be cooled through said cooling coil, recirculation plying heat to said stream 0! fluid. and thermostat means responsive to the temperature of one or said streams to adjust the amount of air so conducted back by said recirculation means and also said means for applying heat to said stream of fluid to prevent the temperature of fluid in a selected temperature range determined means for conducting a part of the stream of air leaving said chamber back to said air inlet,

- means for controlling the amount of air returning through said recirculation means, a heating coil arranged in the stream oi air passing through said chamber, said stream of air being normally heated through heat derived from said stream of fluid passing through said cooling coil,'means for conducting a. heating medium through said heating coil to heat the air passing said cooling coil, and thermostat means responsive to the temperature of one of said streams to'adiust said heating medium conducting means to prevent the temperature of said fluid in said cooling coil from falling below said temperature range.

MARTIN H. OI-STAD.

ALLAN E. WILLIAMS. 

